# Greetings from The On-Line Encyclopedia of Integer Sequences! http://oeis.org/ Search: id:a293047 Showing 1-1 of 1 %I A293047 #4 Oct 09 2017 23:21:57 %S A293047 0,0,0,3,4,15,26,63,120,255,502,1023,2036,4095,8178,16383,32752,65535, %T A293047 131054,262143,524268,1048575,2097130,4194303,8388584,16777215, %U A293047 33554406,67108863,134217700,268435455,536870882,1073741823,2147483616,4294967295,8589934558 %N A293047 Number of odd permutations on {1,2,...,n} with exactly 2 weak excedances. %H A293047 Dmitry Efimov, Determinants of generalized binary band matrices, arXiv:1702.05655 [math.RA], 2017. %F A293047 a(n) = (A000295(n) + (-1)^n * (n-1))/2, n > 0. %F A293047 a(n) = 2^(n-1) - 1 for odd n. %Y A293047 Cf. A000295, A293046. %K A293047 nonn %O A293047 0,4 %A A293047 _Eric M. Schmidt_, Oct 09 2017 # Content is available under The OEIS End-User License Agreement: http://oeis.org/LICENSE